Structure and function of bacterial fatty acid synthetases consisting of multifunctional polypeptide chains. The organisms chosen for these studies are Mycobacterium smegmatis and Corynbacterium dipththeriae. Studies on the mode of action of non-catalytic cytoplasmic proteins that promote membrane-associated transformations of intermediates in the squalene-cholesterol pathway of mammalian liver. The effect of structural modifications of the sterol molecule on function in both artificial and natural membranes. Further definition of the sterol requirement of Mycoplasma capricolum. Effects of variations in sterol structure on the chemistry and on properties of Mycoplasma membranes.